Field of the Invention
The present invention is concerned with adjustable seat backs for bench type automobile seats, normally provided in cars, vans and buses.
In accordance with the present invention, the seat back is movable relative to the seat bottom between a rearwardly extending horizontal full reclining position and a forwardly extending horizon position in which the back of the seat constitutes a horizontal support including an intermediate position in which the seat back is substantially erect herein referred to as the dress-up position.
Means are provided to retain the seat back positively locked in any intermediate position between its erect and its full reclining position. This includes sectors pivoted to a seat frame comprising spaced apart plates referred to as seat mounts and covers, the sectors having arcuate sections of ratchet teeth engageable with locking pawls pivoted between the plates constituting the seat mount and cover. The pawls are engaged by wedge cams connected to interconnected release handles to each end of the seat ratchet which are spring biased in a direction to wedge the pawls into engagement with the ratchet section on the sector.
The wedge angle is such that the locking action is irreversible by forces applied to the seat back. The release handle when moved to full release position by the operator includes a surface engageable with a finger on the pawl to provide for positive displacement of the pawl from the ratchet teeth.
The sectors are provided at both ends of the seat, and are connected to strong counterbalance springs effective to move the seat back to and slightly beyond its full erect or dress-up position. The seat back is adjustable by a seat occupant who releases the cam lock and applies pressure to move the seat back against the counterbalance springs to the desired position, at which time release of the handle permits its spring to move it and the wedge cam to sector locking position.
Since the locking hardware is provided at both ends of the seat and seat back, it is necessary to provide means for releasing the sectors for simultaneous movement. This is accomplished by a torsion tube extending between the ends of the seat back, with connections to the release handles, so that the seat back may be adjusted or manipulated from either end.
The sectors are each provided with hinge plates which are pivotally connected to the upper ends of the sectors, and which are fixedly secured to opposite ends of the seat back frame to provide for forward swinging movement of the seat back from its upward extending position to its forwardly extending position. During movement of the seat back between its erect position and its fully reclining position, the hinge plates are fixedly connected to the sectors by latch cams pivoted to the sectors and latched over studs connected to the hinge plates. The latch cams have camming pins extending into cam slots provided in the seat mounts. The seat mount slots include arcuate portions concentric with the pivot axis of the sectors and camming portions inclined to the arcuate portions operable during limited movement of said sectors forwardly from erect position to cam the latch cams to release the studs on the hinge plates. Thus, as the sectors are spring biased into their forward limiting position, the hinge plates with the seat back secured thereto are released for pivotal movement of the hinge plate relative to the sectors to permit the seat back to move to forwardly extending horizontal position. As the sectors move to release the latch cams, the tooth portions of the sectors move beyond the pawl teeth, which then slide on smooth arcuate surfaces on the sectors.
When the seat back is swung upwardly and rearwardly from its forwardly extending horizontal position, the studs on the hinge plates engage the latch cams, and further movement pivots the sectors, causing the latch cams to be cammed into latching position by the cam slots. When the sectors have pivoted sufficiently to engage the latch cams, the toothed ratchet portions are engaged by the pawls which are wedged in locking position by the spring biased wedge cams.